Atropisomers are important organic frameworks in bioactive natural products, drugs as well as chiral catalysts. Meanwhile, silanols display unique properties compared to their alcohol analogs, however, the catalytic synthesis of atropisomers bearing silanol groups is challenging. Here, we show a rhodium-catalyzed torsional strain-promoted asymmetric ring-opening reaction for the synthesis of α-silyl biaryl atropisomers. The reaction features a dynamic kinetic resolution of C(Ar)-Si bond cleavage, whose stereochemistry was controlled by a phosphoramidite ligand derived from (S)-3-methyl-1-((2,4,6-triisopropylphenyl)sulfonyl)piperazine. This work is a demonstration of an aryl-Narasaka acylation, where the C(Ar)-Si bond cleavage is promoted by the torsional strain of α, α’-disubstituted silafluorene.

A rhodium-catalyzed enantioselective ring-opening/acylation of silafluorenes is reported. The newly developed bulky phosphoramidite ligand, in combination with methanol as the additive, enabled the reaction to create one axial chirality and one silicon-stereogenic center in a highly selective manner by only cleavage of one Si−C bond.

Carbon-carbon activation | Transition-metal | Asymmetric catalysis | Asymmetric synthesis | Ring-opening reaction Catalytic asymmetric transformations involving carbon-carbon bond cleavages open intriguing strategies for the synthesis of chiral complex molecules. The transient organometallic species mainly generate from the oxidative addition of cyclic compounds with low valence metals or from β-carbon elimination of tert-alkoxyl metals. This overview covers the recent advances in transition-metal-catalyzed carbon-carbon bond activation in asymmetric synthesis. Xiufen Bi (left) was born in Anhui, China. She obtained her bachelor degree from Anhui Normal University in 2017. Then she turned to University of Science and Technology of China (USTC) to pursue her PhD degree of organic chemistry under the supervision of Professor Gu. Qiuchi Zhang (middle) was born in Sichuan, China. He received his bachelor degree from USTC in 2014. Then he turned to Nanyang Technological University for his doctoral studies and received PhD degree in 2019 under the supervision of Prof. Tech-Peng Loh. He is currently a post-doctor in Prof. Gu's group at USTC. Zhenhua Gu (right) studied chemistry at Nanjing University and received his PhD degree in Shanghai Institute of Organic Chemistry in 2007 with Prof. Shengming Ma. He conducted his postdoctoral research at University of California Berkeley and University of California at Santa Barbara. In 2012, he began his independent academic career at the USTC with the support of "Thousand Talents Plan". Research in his group is mainly focused on the development of new methods for asymmetric atropisomers and their related natural products synthesis.

Interventions to promote language development in young children are increasingly being delivered within natural environments. In classroom-based programs, free play is often the setting for intervention. Recent research suggests that play context, defined by types of toys available, affects the language and interactive style of both adults and children. In this study, both teacher speech toward toddlers and toddler speech were recorded and analyzed in three classroom play contexts: doll/house play, block/truck play, and large motor play. Significantly different language-use patterns by teachers were found in each area, and these were associated with differences in the rate and nature of child language. Teachers may be best able to implement practices to facilitate child language in play contexts that are compatible with the desired learning goals.